Is post advertising a safe link building method

So how about these websites like payperpost, blogvertise and sponsoredreviews.com. They provide ways for web developers to purchase blog post advertising at affordable onetime fees, which Google views as (paid-links). Even though a couple of these programs hide their blog publishers pretty well, I continue hesitating whether it’s worth the risk. Some pages I’ve tracked using this system seem to rank well while others don’t rank well at all.

Can Google Track those who participate?
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